Contact structure for electric disconnect switch



y 20, 1965 R. J. BERTLING 3,196,226

CONTACT STRUCTURE FOR ELECTRIC DISGONNECT SWITCH Filed Jan. 22, 1962 3 Sheets-Sheet l INVEN TOR.

Fonwla J Bertlzy' BY July 2 1965 R. J. BERTLING 3,

CONTACT STRUCTURE FOR- ELECTRIC DISCONNECT SWITCH Filed Jan. 22, 1962 3 Sheets-Sheet 2.

y 20, 1965 J. BERTLING 3,196,226

CONTACT STRUCTURE FOR ELECTRIC DISCONNECT SWITGFI Filed Jam-22, 1962 s Sheets-@heef 3 IN VEN TOR. PondZd Benin) United States 3 196.226 C(BNTA'CT FOR ELEQTRKC DESGNNET Svil'lilld Ronald I. Herding, @ak Eireelr, Win, assignor to McGraw- Edison Company, Milwaukee, Wis, a corporation of Delaware Filed Jan. 22, 1962, Ser. No. 167,649 7 Claims. (Ci. Ziill-dh) This invention relates to electric switches and, more particularly, to contact structure for electric disconnect switches.

Electric disconnect switches generally comprise a switch blade pivotally mounted for movement into and out of engagement with a contact jaw. The switch blade and contact jaw are generally mounted on spaced apart insulators which electrically insulate the switch from the metallic or wooden supporting structure. In center break switches the contact jaw is also pivotally mounted on a conductive arm and contact with the switch blade is made at a point intermediate the supporting insulators.

it is an object of the invention to provide a center break switch in which the frictional forces between the switch blade and the contact jaw, produced during opening and closing operations, are parallel to the switch blade axes.

A still further object of the invention is to provide a disconnect switch having a switch blade and a contact jaw wherein the number of current interchange points is reduced.

Another object of the invention is to provide an air disconnect switch wherein the direction of current flow between the switch blade and the contact jaw is parallel to the switch blade axis.

Still another object of the invention is to provide a center break air disconnect switch in which contact pressure is not substantially affected by minor alignment deviations between the switch blade and the contact jaw.

Another object of the invention is to provide a disconnect switch having first and second spaced apart termirials, an elongate conductive member afiixed at one end to these terminals, means for producing relative angular movement of the conductive members between first and second relative angular positions, wherein one of the conductive members has a surface formed on its other end and a plurality of contact fingers are mounted in intimate contact with the surface and extend toward said other member and wherein the other end of said other member has a contact surface formed thereon which is engageable between the contact fingers when the members are in their first relative angular position.

These and other objects and advantages of the instant invention will become more apparent from the detailed description thereof taken with the accompanying drawings in which:

FIG. 1 is a side elevational view of the an air disconnect switch according to the instant invention;

FIG. 2 is a top plan view of the switch shown in FIG. 1;

H8. 3 shows the contact structure of the switch shown in FIGS. 1 and 2, with parts broken away;

FIG. 4 is a view taken along lines 44 of FIG. 3; and

FIG. 5 is a view taken along lines 55 of FIG. 3.

PEG. 1 shows a rotating insulator type center break disconnect switch incorporating a preferred embodiment of the instant invention and which is designated generally by the reference numeral 1'3. Switch ill is shown mounted on a horizontal channel member 12 and includes a pair of insulators i3 and M- which are mounted on hearing assemblies l5 and 16 respectively for rotation about parallel, spaced apart, vertical axes, under the action of an operating mechanism 123. A mounting bracket 2% and a clamping assembly 251 support a switch blade 22- on the upper ice end of the insulator 13 for rotation in a horizontal plane. In addition, an identical mounting bracket 24 and clamping assembly 25 support a conductive arm 26 which carries a contact jaw 23 at its end for engagement by the end of the switch blade 22.

Each of the bearing assemblies 15 and 11.6 is identical and each has a laterally extending operating lever 39 and 31, respectively, which are interconnected by a linkage assembly 32. The assembly 32 includes a turnbuckle pipe 3 whose opposite ends thread-ably engage the stem 35 of a yoke member 37 which pivotally engages the ends i the operating levers 3d and 31. Each of the stems 35 and the ends of the turnbuck e pipe 34 are threaded in opposite directions so that the length of the linkage 32 will either increase or decrease when the pipe 345 is rotated in one direction or the other. The bearing 16 also has a second laterally extending operating arm 39 which is coupled to a switch operating mechanism (not shown). It can be seen that rotation of the lever 39 in a counterclockwise direction will rotate the insulator l4 and the lever arm 31 in the same direction. Rotation of the arm 31 will also rotate the operating arm 30 and the insulator 13 in a clockwise direction through the agency of the linkage 2'52. As a result, the switch blade 22 and the contact jaw 23 will disengage and rotate in opposite directions from their positions shown by full lines in FIG. 2 to their positions shown by phantom lines. For a more complete description of the bearing assemblies 15 and 16, the turnbuckle pipe 34 and the yoke members 37, reference is made to Patent 2,878,331 to T. A, Fjellstedt et al., which is assigned to the assignee of the instant invention.

Arcing horns 4'6 and 41, which are mounted on the switch blade 22 and contact arm 26, respectively, provide a parallel current path around the contact jaw 23 and are constructed and arranged to disengage after switch blade 22 has disengaged from the contact jaw 28 o that no arc will be struck between the primary current carrying memhere in the event that the switch lid) is opened under load.

The improvements which comprise the present invention consist of the means for mounting the contact jaw 28 at the end of the conductive arm 26 and for forming the contact tip 4 6 at the end of the switch blade 22.

As seen in FIGS. 3 and 4, the switch blade 22 and the conductive arm 26 are formed from substantially identical tubular stock in which a pair of parallel slits so and 5%, respectively, have been formed in each of their free ends and at their opposite lateral sides. The end portions 52 of the conductive arm 26 are flattened and bent inwardly toward each other to provide a substantially planar surface 52 presented toward the other arm 22 for mounting the contact jaw 28. A metallic backup plate 53 is disposed behind the bent ends SE of the conductive member 26 to provide mechanical support for the contact jaw 23 and a heat sink for the current interchange joint formed therea-t.

in a similar manner, the contact tip 44 of the switch blade 22 is fanned by flattening its split ends 55 and then forming each into a shallow transverse arc whose inner surfaces are brazed to a metallic backup plate 56 which also provides mechanical support and a heat sink for the current interchange between the switch blade 22 and the contact jaw 2%. As seen in FIGS. 3 and 4 a pair of end caps 58 are afiixed to the lateral sides of the backup member 56 for facilitating movement of the contact tip 44 into the contact jaw 23.

The contact jaw 28 includes a pair of angular contact fingers 6% whose free. ends 61 flare outwardly for receiving the switch blade contact tip 44 and whose fixed ends 62 are bent inwardly for attachment to the surface 5?. by means of screws 6 which extend into the backup plate 53. The contact fingers so are resiliently urged into high pressure engagement with the switch blade tip 44 by leaf type spring assemblies 65. The spring assemblies 65 each includes a plurality of leaf springs or which engage the contact fingers oil at one end and the backup plate 53 at their'othen, The leaf springs as are loaded by means of a tie bar 63 which extends through the opposed leaf spring assemblies 65 on each contact finger 6t and which are retained in bearing relation with said assemblies by means of retainer pins 6'9 extending transversely through each end. {)ne end "it? of each of the longest leaf springs 65 is bent for engagement with a groove 72 formed in each of the lateral sides of the backup plate 53. The other end 74 of said leaf spring engages a pressure pad 76 on the intermediate portion of the contact fingers 6i It will be appreciated from the foregoing discussion that current flow from the switch blade 2.; to the conductive arm 26 is from the ends SS'of the switch blade 22, to the contact fingers 6b. and thence to the surface 52 formed on the conductive arm 25. As a result, there are only two current interchange points between these members so that substantially cooler switch operation is obtainable than with switches having a greater number of current interchange points. In addition, the contact structure above described eliminates 'a number of bolted and clamped parts found in prior art devices for supporting the contact jaw and contact tip, thereby substantially reducing maintenance and manufacturing expense.

it can be seen, also, that the direction of current flow through the switch between the switch blade 22 and the conductive arm 26 is in a direction parallel to these members. Consequently, electromagnetic forces incident to high momentary currents through the switch act in a direction longitudinal to the switch blade 22 and the conductive arm 26 so that the tendency for the switch to open under such forces is substantially nonexistent.

Also, because of the configuration of the contact tip 48 and the contact jaw 28 the frictional forces therebetween during a closing operation will act in a direction substantially parallel to the axis of the switch blade 22 and the conductive arm 26. This allows substantially easier switch operation because of the lower torque developed around the axis of the bearings 15 and to than in the case of some prior art center break switches wherein this frictional force acts in a direction perpendicular to the axis of the members 22 and 26.

While only a single embodiment of the invention has been illustrated and while the invention has been discussed in relation to one particular typeof switch, it is not intended that the invention be limited thereby, but only by the scope of the appended claims.

I claim:

'1. A disconnect switch having first and second spaced terminals, means for rotating said terminals in opposite directions, a unitary conductive arm afilxed 'at one end to each of said terminals, said terminals each having a first angular position wherein said arms extend toward each other and are substantially coaxial, the other ends of each of said conductive arms having a pair of longitudinal slits in the opposite sides thereof, the split ends of one of said arms being bent inwardly toward the axis of said arm to provide a substantially planar surface normal to said axis and presented toward the other end of said other arm, a plurality of contact fingers mounted in intimate contact with said surface and extending toward said other arm, the split end of said other arm being flattened to form contact surfaces substantially parallel to said surface and engageable between said contact fingers to provide line contact therewith when said terminals are in their first angular position, the end of said other arm being out of engagement with said contact fingers when said arms are each in a second angular position.

2. A disconnect switch having first and second spaced terminals, a hollow unitary conductive arm atfixed at one its axis and presented toward the other end of said other arm, a first metallic member affixed to said pianar portion interiorly of said arm to provide a support therefor, said first metallic member being substantially coextensive with said planar portion'and having a substantially greater thickness than the material forming said arm,'a plurality of contact fingers, means engaging said first metallic member'for affixing said contact fingers in electrical contact with said planar portion, the other end of said other arm having a pair of transverse surfaces formed on the opposite sides thereof and engageable between said contact fingers to provide line contact therewith when said terminals are in their first angular position, the end of said other arm being out of engagement with said contact fingers when said arms are each in a second angular position,'a second metallic member disposed between said transverse surfaces on said other arm, said second member being substantially coextensive with said transverse surfaces and having a substantially greater thickness than the material forming said other arm, and spring means engaging said first metallic member and said contact fingers for urging said fingers into high pressure engagement with said transverse. surfaces. 3. A disconnect switch having first and second space terminals, a hollow unitaryconductive arm affixed at one endto each of said terminals, means for rotating said terminals between first and second angular positions, said arms extending toward each other and being substantially coaxial when said terminals are in a first angular position, the other ends of each of said conductive arms being split by a pair of longitudinal slits in the opposite sides" thereof, the split end of one of said arms being bent inwardly toward the axis of said arm to provide asubstantially planar surface normal to said axis and presented toward the other end of said other arm, a first metallic member affixed to said planar surface to provide a support therefor, a plurality of contact fin ers, means engaging said first metallic member for affixing said contact fingers in electrical contact with said surface, the

split ends of said other arm being flattened and engageable between said contact fingers to provide line contact therewith when said terminals are in their first angular position, the end of said other arm being out of engagement with said contact fingers when said arms are each in a second angular position, a second metallic member disposed between the flattened portions of said other arm, and spring means engaging said first metallic member and said contact fingers for urging said fingers into high pressure engagement with said flattened portions of said other arm.

4. A disconnect switch having first and second spaced terminals, a hollow unitary conductive arm afiixed at' co-axial when said terminals are in a first angular posi tion, one of said arms having a generally planar portion formed on its other end and substantially normal to its axis and facing the other end of said other arm, a plurality of contact fingers alfixed to said generally planar portion and extending in a direction generally parallel to the axis thereof, the other end of said other arm having a pair of transverse surfaces formed on the opposite sides thereof and engageable between said contact fingers to provide line contact therebetween when said terminals are in their first angular position, the end of said other arm being out of engagement with said contact finger-s when said arms are each in a second angular posit-ion, a metallic member disposcd between said transverse surfaces on said other arm, said metallic member being substantially co-extensive with said transverse surfaces and having substantially greater thickness than the material forming said other arm, and spring means engaging said contact fingers for urging said contact fingers into high pressure engagement with said transverse surfaces.

5. A disconnect switch having first and second spaced terminals, a hollow unitary conductive arm affixed at one end to each of said terminals, means for rotating said terminals between first and second angular positions, said arms extending toward each other and being substantially co-aXial when said terminals are on a first angular position, one of said arms having a planar portion formed on the other end thereof and substantially normal to its axis and presented toward the other end of said other arm, a metallic member affixed to said planar portion interiorly of said arm to provide support therefore, said metallic member being substantially co-extensive with said planar portion and having a substantially greater thickness than the material forming said arm, a plurality of contact fingers, means engaging said metallic member for affixing said contact fingers against said planar portion, the other end of said other arm having a pair of transverse surfaces formed on the opposite sides thereof and engageable between said contact fingers to provide line contact therebetween when said terminals are in their first angular position, the other end of said other arm being out of engagement with said contact fingers when said arms are each in a second angular position, and spring means engaging said metallic member and said contact fingers for urging said contact fingers into high pressure engagement with said transverse surfaces.

6. A disconnect s vitch having first and second spaced terminals, a hollow unitary conductive arm affixed at one end to each of said terminals, means for rotating said terminals between first and second angular positions, said arms extending toward each other and being substantially co-axial when said termials are in a first angular position, the other end of one of said conductive arms being split by a pair of longitudinal slits in the opposite sides thereof, the split ends of said one arm being bent inwardly toward the axis of said arm to provide a sub stantially planar surface normal to said axis and presented toward the other end of said other arm, a metallic member affixed to said planar surface to provide a support therefor, a plurality of contact fingers, means engaging said metallic member for afiiidng said con-tact fingers in electrical contact with said surface, the other end of said other arm having a pair of transverse surfaces formed on the opposite sides thereof and engageable between said contact fingers to provide line contact therewith when said terminals are in their first angular position, the end of said other arm being out of engagement with said contact fingers when said terminals are in a second angular position, and spring means engaging said metallic member and said Contact fingers for urging said fingers into high pressure engagement with the flatten d portions of said other arm.

'7. A disconnect switch having first and second spaced terminals, a hollow unitary conductive arm affixed at one end to each of said terminals, means for rotating said terminals between first and second angular positions, said arms extending toward each other and being substantially co-axial when said terminals are in a first angular position, the other end of one of said conductive arms having a planar portion formed thereon and substantally normal to its axis and presented toward the other end of said other arm, a plurality of contact fingers afiixed to the planar portion of said one arm and extend ing generally parallel to said axis, the other end of said other conductive arm being split by a pair of longitudinal slits which are flattened and engageable between said contact fingers to provide line contact therewith when said terminals are in their first angular position, the end of said other arm being out of engagement with said contact fingers When said arms are each in a second angular position, a metallic member disposed between the fiattened portions of said other arm, and spring means engaging said contact fingers and the other end of said one arm for urging said fingers into high pressure engage ment with the flattened portions of said other arm.

References Cited by the Examiner UNITED STATES PATENTS 1,835,696 12/31 Croft 200-48 2,094,037 9/37 Wilkins 20048 BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFER, Examiner. 

4. A DISCONNECT SWITCH HAVING FIRST AND SECOND SPACED TERMINALS, A HOLLOW UNITARY CONDUCTIVE ARM AFFIXED AT ONE END TO EACH OF SAID TERMINALS, MEANS FOR ROTATING SAID TERMINALS BETWEEN FIRST AND SECOND ANGULAR POSITIONS, SAID ARMS EXTENDING TOWARD EACH OTHER AND BEING SUBSTANTIALLY CO-AXIAL WHEN SAID TERMINALS ARE IN A FIRST ANGULAR POSITION, ONE OF SAID ARMS HAVING A GENERALLY PLANAR PORTION FORMED ON ITS OTHER END AND SUBSTANTIALLY NORMAL TO ITS AXIS AND FACING THE OTHER END OF SAID OTHER ARM, A PLURALITY OF CONTACT FINGERS AFFIXED TO SAID GENERALLY PLANAR PORTION AND EXTENDING IN A DIRECTION GENERALLY PARALLEL TO THE AXIS THEREOF, THE OTHER END OF SAID OTHER ARM HAVING A PAIR OF TRANSVERSE SURFACES FORMED ON THE OPPOSITE SIDES THEREOF AND ENGAGEABLE BETWEEN SAID CONTACT FINGERS TO PROVIDE LINE CONTACT THEREBETWEEN WHEN SAID TERMINALS ARE IN THEIR FIRST ANGULAR POSITION, THE END OF SAID OTHER ARM BEING OUT OF ENGAGEMENT WITH SAID CONTACT FINGERS WHEN SAID ARMS ARE EACH IN A SECOND ANGULAR POSITION, A METALLIC MEMBER DISPOSED BETWEEN SAID TRANSVERSE SURFACES ON SAID OTHER ARM, SAID METALLIC MEMBER BEING SUBSTANTIALLY CO-EXTENSIVE WITH SAID TRANSVERSE SURFACES AND HAVING SUBSTANTIALLY GREATER THICKNESS THAN THE MATERIAL FORMING SAID OTHER ARM, AND SPRING MEANS ENGAGING SAID CONTACT FINGERS FOR URGING SAID CONTACT FINGERS INTO HIGH PRESSURE ENGAGEMENT WITH SAID TRANSVERSE SURFACES. 